A single dose of radiotherapy delivered at the time of surgery by way of targeted intraoperative radiotherapy should be considered as an alternative to external beam radiotherapy delivered over several weeks postsurgery for selected patients with early breast cancer, found a study published online June 5 in the Lancet.
Jayant S. Vaidya, PhD, from the division of surgery and interventional science at the University College London, and colleagues compared targeted intraoperative radiotherapy with the conventional policy of whole breast external beam radiotherapy.
“After breast-conserving surgery, 90 percent of local recurrences occur within the index quadrant despite the presence of multicentric cancers elsewhere in the breast. Thus, restriction of radiation therapy to the tumor bed during surgery might be adequate for selected patients,” they explained.
Beginning on March 24, 2000, the researchers started the randomized, targeted intraoperative radiotherapy TARGIT-A trial. Women age 45 years or older with invasive ductal breast carcinoma undergoing breast-conserving surgery were enrolled from 28 centers in nine countries.
Vaidya and colleagues randomly assigned patients in a 1:1 ratio to receive single-dose targeted intraoperative radiotherapy with intrabeam (1,113 patients) or whole breast external beam radiotherapy (1,119 patients), with blocks stratified by center and by timing of delivery of targeted intraoperative radiotherapy.
The researchers, physicians and patients were not blinded to the assigned treatment method and the researchers explained that in approximately 15 percent of patients, postoperative discovery of predefined factors (e.g., lobular carcinoma) could require the addition of external beam radiotherapy to targeted intraoperative radiotherapy. The researchers established pathologically confirmed local recurrence in the conserved breast as the primary outcome.
According to the authors, of the included 996 patients who underwent assigned treatment in the targeted intraoperative radiotherapy group, 854 (86 percent) received targeted intraoperative radiotherapy only and 142 (14 percent) received targeted intraoperative radiotherapy plus external beam radiotherapy. Ninety-two percent or 1,025 patients in the external beam radiotherapy group received the assigned treatment.
Follow-up was completed on these patients at three months, six months and then every six months up to five years. At four-year follow-up, Vaidya and colleagues observed six local recurrences in the intraoperative radiotherapy group and five in the external beam radiotherapy group. In addition, the frequency of any complications and major toxicity was determined to be similar in the two groups.
For targeted intraoperative radiotherapy, 37 patients experienced major toxicity compared to 44 patients from the external beam radiotherapy group. Moreover, radiotherapy toxicity (Radiation Therapy Oncology Group grade 3) was lower in the targeted intraoperative radiotherapy group (six patients) than in the external beam radiotherapy group (23 patients).
Noting the similar rates of complications in the targeted intraoperative radiotherapy and external beam radiotherapy groups, the authors said that the finding showed targeted intraoperative radiotherapy to be a safe alternative. In addition, Vaidya and colleagues estimated that the treatment could provide cost saving opportunities of approximately $23,000,000 per year, especially for countries with waiting lists for postoperative radiotherapy.
The researchers concluded: “Our results bring us closer to a scenario in which a patient with early breast cancer might complete all her local treatment, surgical excision, sentinel lymph node biopsy and radiotherapy at one or two visits, without having to stay overnight in a hospital bed…These advances could substantially reduce the effect of a breast cancer diagnosis and treatment on a woman’s life.”